Current treatment of severe acute respiratory failure relies on intubation, and mechanical pulmonary ventilation to improve oxygenation and decrease work of breathing. Adverse effects therefrom are many. They are progressive, and include aspiration, tracheal injury, decreased tracheal mucus velocity, barotrauma, and nosocomial pneumonia. We have developed a new method of pulmonary ventilation that obviates intubation and the use of MV: Spontaneous Airway Pressure Release Ventilation (S-APRV). When fresh air/oxygen was introduced through a percutaneously introduced mini-tracheostomy (4 mm) catheter into the trachea, we found that breathing rate (in sheep) greatly decreased, while the breathing pattern changed. During inspiration, the glottis remained closed (sic), with inflation of lungs through the force provided by the stream of air/oxygen. During expiration, the glottis opened. Commonly, the inspiration/expiration ratio (I/E ratio) was greatly prolonged, with a very short expiratory phase. The respiratory rate was greatly reduced, with mean airway pressure elevated. S-APRV, as now used, requires no electrical controls/power. In studies of oleic acid-induced severe ARF in sheep on S-APRV, we found a great reduction in the respiratory rate, progressive improvement in arterial blood gases, and weaning to room air ventilation within 8-12 h of such treatment. From measurements of pleural pressure changes we infer that effort of breathing is reduced from 50 to 90%. The trachea was free of mucus, a benefit from the use of a special Reverse Thrust Catheter (RTC). The benefits of the S-APRV system include: 1) no need for tracheal intubation; 2) eating, drinking, and vocalization are not affected; 3) cough is preserved; 4) breathing is controlled by the patient and the decreased effort of spontaneous breathing is greatly decreased. We believe S-APRV can be used not only in the management of severe ARF, but also may find application in neuromuscular disorders, and in COPD.